Suppose we have a sheet of paper partitioned in a grid of squares.
We label squares with coordinates (i,j).
Square (0,0) is the leftmost top square.
Square (i,j) is the square in row i+1 and column j+1.
For example,
square (1,2) is the second square from the top row,
in the third column.
On this sheet we want to draw a letter E of 10 squares high
and 5 squares wide. The sheet contains at least 5 rows and 10
columns of squares.
There are three primitive drawing instructions:
- pen down: put the pen down;
- pen up: put the pen up; and
- goto (i,j): go to square (i,j).
If the pen is down, then goto will draw a line from the
current square to square (i,j).
- Make a drawing to illustrate the movements of the pen.
Instead of lines use vectors and label the vectors with 1, 2, ...
to mark the order of movements.
- Write all instructions for the algorithm to draw a E
of 10 squares high and 5 squares wide,
using only the three primitive drawing operations.